Some of the criticism was launched even before the president returned home, violating an American political tradition, famously articulated by the late Republican Sen. Arthur Vandenberg of Michigan, that "politics stops at the water's edge."

On his first trip as president to the region, Obama acted according to what he explained could be called the Obama Doctrine -- recognizing that while the United States is the strongest nation on earth, it needs to work with other countries, that cooperation will ultimately benefit the United States and that the country needs to confess to its sins when it fails to meet up to its ideals.

But the moment that took the spotlight -- and probably drew the most criticism -- was his handshake with Venezuelan President Hugo Chavez, who has openly denounced U.S. foreign policies, once called President Bush "the devil" and has often rallied the region in criticizing the United States. At the summit, he even presented Obama with a book assailing the United States for exploiting Latin America.

Obama approached the Venezuelan president to shake his hand, and the two seemed quite collegial in photographs Chavez rushed to post on his country's Web site. Obama's critics chided the president for smiling widely and touching Chavez on the shoulder as they shook hands.

"You have to be careful who you are seen joking around with. It was irresponsible of the president to be seen joking around with the president [Chavez]," said Sen. John Ensign, R-Nev., former chairman of the National Republican Senatorial Committee, to CNN Sunday morning while Obama was conducting meetings in Trinidad.

On Monday, well after Obama's return, former Republican House Speaker Newt Gingrich of Georgia said Obama's interaction with Chavez sends a poor message to U.S. foes.

"What I find distressing is that the administration opposes opening up oil exploration," he said on NBC's "Today Show." "But yet Obama has bowed to the king of Saudi Arabia and now reached out to Chavez," who has been conducting a "a vicious anti-American campaign."

The White House said Obama was only being courteous, and the president himself scoffed at any idea that his being polite to Chavez played into his hands in any way.

"I think it's just that President Chavez is better at positioning the cameras," Obama joked.

"It is possible we will begin evaluating the designation of an ambassador in the United States," Chavez announced Saturday. "We want to move in that direction. We take Obama at his word, with the one difference we have: We are socialists."

The State Department said Chavez approached Secretary of State Hillary Clinton, and the two discussed returning ambassadors to their respective posts in Caracas and Washington.

"This is a positive development that will help advance U.S. interests, and the State Department will now work to further this shared goal," the State Department said in a statement.

Defending Diplomacy

Venezuela is the fourth-largest exporter oil to the United States, and many at home feel it is in the country's interest to revive relations. The issue of how the United States should deal with Chavez was a large part of the 2008 campaign.

"I don't want to see the power and prestige of the United States president put at risk by rushing into meetings with the likes of Chavez and Castro and Ahjmenanjad," then-presidential candidate Hillary Clinton told CNN in 2007.

In keeping with his doctrine and campaign rhetoric, Obama said that reaching out to critics in Latin America would only benefit the United States.

"We had this debate throughout the campaign, and the whole notion was that if we showed courtesy or opened up dialogue with governments that had previously been hostile to us, that that somehow would be a sign of weakness. The American people didn't buy it. ... And there's a good reason the American people didn't buy it -- because it doesn't make sense," he said Sunday.

The administration said it would like to see the Cuban government take steps on a number of issues, including releasing political prisoners, discontinuing the practice of taking money from remittances and do more to open up freedom of the press. White House Press Secretary Robert Gibbs said Obama was "pleased with the reaction" he received from Cuba, but it depends what measures they take next.

"The fact that you had Raul Castro say he's willing to have his government discuss with ours not just issues of lifting the embargo, but issues of human rights, political prisoners, that's a sign of progress. ... And so we're going to explore and see if we can make some further steps," Obama said.

Only a few years ago, Obama supported lifting the embargo.

"It's failed to provide the source of raising standards of living and squeezes the innocent," and "it's time for us to acknowledge that this policy has failed," he said in 2004.

"Well, 2004, that seems just eons ago. What was I doing in 2004?" he joked. (He was running for Senate). "It is my belief that we're not going to change that policy overnight. And the steps that we took, I think we're constructive in sending a signal that we'd like to see a transformation."

Some Americans feel that it's time the United States relax restrictions on Cuba. A delegation of lawmakers visited the country this month and pressed Obama to rethink the decades-old policy. Others, especially Cubans in Miami, feel that such a move will only give more leverage to the Castro family.

"How do you mend relationships with someone who actively hates your country?" Gingrich said Monday. "Cuba releases zero prisoners, yet we make nice with Cuba. I'm for doing things methodically and calmly ... things that will work, but I'm not for deluding myself about smiles and words."

Some Republicans believe that Cuba needs to take the first step in mending relations.

"Release the prisoners and we'll talk to you," Sen. Lindsey Graham, R-S.C., said on "Fox News Sunday." "Simple as that. Put up or shut up."

Intricate Encounters

Cuba and Venezuela aside, some other moments also drew criticism, such as Obama sitting through a 52-minute airing of grievances by Nicaraguan President Daniel Ortega.

Some unnamed Bush advisers leaked blind quotes to some media outlets, sneering that Bush never would have sat through such a diatribe.

In another unusual incident, Bolivian President Evo Morales demanded that Obama denounce an assassination attempt on him, lest he think the United States was behind it.

When Obama held his press conference Sunday, he -- unprompted by any media questions on the subject -- denied any such act.

"I just want to be absolutely clear that I am absolutely opposed and condemn any efforts at violent overthrows of democratically elected governments -- wherever it happens in the hemisphere," Obama said. "That is not the policy of our government."

Obama's approach is markedly different than that of his predecessor, President Bush, and it remains to be seen how it plays out politically.

"Over the last few days we've seen potential positive signs in the nature of the relationship between the U.S., Cuba and Venezuela, but as I've said before, the test for all of us is not simply words but also deeds. I do believe that the signals sent so far provide at least an opportunity for frank dialogue on a range of issues, including critical areas of democracy and human rights through the hemisphere," Obama said at a news conference closing the summit.